1. Field of the Invention
The present invention relates to a preset counter apparatus for use, for example, in copying machines for setting and displaying the number of copies to be made in a continuous mode of operation.
2. Description of the Prior Art
Preset counters heretofore generally used in copying machines for setting the number of copies to be made continuously are frequently those of a mechanical rotary type comprising, for example, a setting dial and a ratchet wheel in combination. The dial is rotated by one division of its scale for every copying cycle and adapted to turn off a switch for continuing the copying operation when rotated to its final position. However, mechanical counter apparatus of this type generally requires a mechanical coupling mechanism for driving the apparatus associated with the copying operation, and further has a drawback of being complex in construction and expensive. Experience has shown that these devices are prone to malfunctions and are usually limited to approximately 20, as the largest, number of copies that can be set. Thus the use of this type of apparatus involves many problems.
The progress of electronic technology in recent years, has made available IC, LSI and like elements with an increased degree of component integration and a performance of enhanced stability at reduced costs. These electronic elements are widely used for controlling mechanical apparatus, such as copying machines. Such elements have also found use in electronic counters, which in combination with seven-segment number displays for indicating the count of the counter, combine to provide preset counter apparatus for copiers.
When electronic counters are used, the number of copies is usually set by ten keys to provide the numbers "0" to "9". In a case where the circuit or program for the counter is designed according to a comparison system, the set value is stored in a memory, and a signal which is emitted every copying cycle, is counted. When the count matches the stored value, the copying operation is discontinued. (U.S. Pat. No. 3,815,990, Newcomb et al., discloses a system of this type although the counter disclosed is not electronic. Alternatively when a subtraction system is resorted to, a decrement is subtracted from the preset value of the counter for every copying cycle, and the copying operation is discontinued when the count on the counter has been reduced to "0" such as disclosed in U.S. Pat. No. 4,105,914, Murata et al. In either case, the counter is associated with the copying operation only electrically, and the maximum number of copies to be made can be selected as desired, so that the electronic counter is free of many of the prior problems encountered with the foregoing mechanical counter apparatus. Accordingly counter apparatus incorporating such an electronic counter or programed control system are widely used in copying machines, etc.
However, with LSI's, microcomputers, etc. coming into wider use, copying machines and the like including electronic counters of the above type are also adaptable for more versatile functions in a copying operation especially when provided with a larger number of keys or displays for imputing and displaying various instructions or selection, by the user. There is also a tendency to provide these keys and displays concentrically on a single operation panel to render the machine easy and efficient to operate. This approach, however, leads to an increase in the area or size of the operation panel, with a greater likelihood of creating handling or manipulation errors and an increased production cost. These new problems are difficult to overcome, especially in the case of compact copying machines wherein only a limited amount of space is available on the operation panel and which must meet limitations with respect to production cost.
To solve the above problems, an apparatus has been proposed which has three input keys, namely an UP key, a DOWN key and a CLEAR key, as disclosed in the Published Japanese patent application No. Sho 54-145545 (1979). Every time the UP key or the DOWN key is depressed or when the key is held depressed position, the numerical value shown on a seven-segment number display is increased or decreased, while the CLEAR key, when depressed, returns the displayed value to "1". This proposed apparatus nevertheless is very cumbersome to use since when the number of copies to be set is large, the key must be depressed a large number of times or held in a depressed position for a prolonged period of time.
Thus the prior art is still seeking an optimimum counter apparatus for copying machines.